Dual damascene metal interconnects may enable reliable low cost production of integrated circuits using sub 0.18 micron process technology. To enable such interconnects to realize their full potential, one method for making a semiconductor device involves a first etched region (e.g., a via or trench) that is filled with a sacrificial light absorbing material (SLAM), after that region has been formed within a dielectric layer. The SLAM may comprise a dyed spin-on-glass (SOG) that has dry etch properties similar to those of the dielectric layer and light absorbing properties that enable the substrate to absorb light during lithography. After the first etched region is filled with the SLAM, a second etched region (e.g., a trench if the via is already formed or a via if the trench is already formed) is formed within the dielectric layer. Most of the SLAM may be removed as that second etched region is formed. Remaining portions of the SLAM are removed by a subsequent wet etch procedure.
The SLAM process reduces, or eliminates, substrate reflection and the need for high etch selectivity. However, material defects in the SLAM and SOG materials may adversely affect dual damascene via and trench formation. Current methods known in the art for the functional characterization of SLAM and SOG materials involve indirect methods that provide characterization based on optical or surface analysis. However, these methods are inadequate because they fail to provide information about what the specific defects in the material may be.